1. Field of the Invention
The present invention relates generally to an image display apparatus, and is directed more particularly to an image display apparatus for projecting onto a projection screen an enlargement of an image reproduced on the picture screen of a cathode ray tube.
2. Description of the Prior Art
It has been proposed to provide an image display apparatus of the projection type, which, as shown on FIG. 1 of the drawings, consists of a cathode ray tube 1 for providing the image to be projected, a reflecting mirror 2, a lens 3 and a projection screen 4. An enlargement of the image reproduced on the picture screen of cathode ray tube 1 is projected through the mirror 2 and lens 3 onto the projection screen 4. In this case, a cathode ray tube of high brightness is used as the cathode ray tube 1.
In general, it is known that a screen which is wide in the lateral direction is coincident with a man's visual field, rich in ambience and capable of interesting visual effects as in Cinemascope (Trade Name) and so on. Thus, it is desired that a projection type display apparatus be capable of producing a wide picture.
In the art, however, since the television video signal of the standard system is selected such that its picture screen size is 3:4 in aspect ratio, the picture projected on the screen 4 from the cathode ray tube 1 in the display apparatus is also 3:4 in aspect ratio, if the prior art display apparatus is not modified.